Position detecting device, liquid ejecting apparatus and method of detecting smear of scale

Abstract

A position detecting device for detecting a position of an object, includes a light emitting portion that emits light, a light receiving portion that receives the light from the light emitting portion, and a scale that is arranged between the light emitting portion and the light receiving portion, and includes a position detecting pattern and a smear detecting pattern. The position detecting pattern has a first light transmitting portion for transmitting the light from the light emitting portion and a first light interception portion for intercepting the light from the light emitting portion which are alternately arranged in a detection range of the object. The smear detecting pattern for detecting smear of the scale has a second light transmitting portion for transmitting the light from the light emitting portion and a second light interception portion for intercepting the light from the light emitting portion which are alternately arranged.

1. A position detecting device for detecting a position of an object, comprising:
 a light emitting portion that emits light; 
 a light receiving portion that receives the light from the light emitting portion; 
 a scale that is arranged between the light emitting portion and the light receiving portion, and includes a position detecting pattern and a smear detecting pattern; 
 a control portion which determines position from the position detecting pattern and determines smear from the smear detecting pattern; and 
 a sensor position switching unit that moves a photosensor having the light emitting portion and the light receiving portion to switch a state of detecting the position detecting pattern and a state of detecting the smear detecting pattern, 
 wherein the position detecting pattern has a first light transmitting portion for transmitting the light from the light emitting portion and a first light interception portion for intercepting the light from the light emitting portion which are alternately arranged in a detection range of the object, 
 wherein the smear detecting pattern for detecting smear of the scale has a second light transmitting portion for transmitting the light from the light emitting portion and a second light interception portion for intercepting the light from the light emitting portion which are alternately arranged, 
 wherein the scale is a liner scale having a long plate shape, and 
 wherein the smear detecting pattern is arranged at an outer side of the position detecting pattern in a longitudinal direction of the linear scale. 
 
     
     
       2. A position detecting device for detecting a position of an object, comprising:
 a light emitting portion that emits light; 
 a light receiving portion that receives the light from the light emitting portion; 
 a scale that is arranged between the light emitting portion and the light receiving portion, and includes a position detecting pattern and a smear detecting pattern; 
 a control portion which determines position from the position detecting pattern and determines smear from the smear detecting pattern; and 
 a sensor position switching unit that moves a photosensor having the light emitting portion and the light receiving portion to switch a state of detecting the position detecting pattern and a state of detecting the smear detecting pattern, 
 wherein the position detecting pattern has a first light transmitting portion for transmitting the light from the light emitting portion and a first light interception portion for intercepting the light from the light emitting portion which are alternately arranged in a detection range of the object, 
 wherein the smear detecting pattern for detecting smear of the scale has a second light transmitting portion for transmitting the light from the light emitting portion and a second light interception portion for intercepting the light from the light emitting portion which are alternately arranged, 
 wherein the scale is a linear scale having a long plate shape, and 
 wherein the smear detecting pattern is arranged so as to be contiguous to the position detecting pattern in a width direction of the linear scale.